Ethernet VPN (EVPN) and Provider Backbone Bridging EVPN (PBB-EVPN) are next generation solutions that provide Ethernet multipoint services over MPLS networks. EVPN uses the Border Gateway Protocol (BGP) as control-plane for MAC address signaling/learning over the core as well as for access topology and VPN endpoint discovery. EVPN expands current existing Virtual Private LAN Services offerings by using control-plane based MAC learning over the core.
In EVPN networks, a software MAC address table is maintained in the firmware of network switches and/or other router devices. This MAC address table contains the MAC addresses learned on all the interfaces of routers and Ethernet access switches. Dynamic MAC address learning occurs when the bridging data path encounters an ingress frame whose source address is not present in the MAC address table for the ingress service instance. In EVPN, the system learns addresses on access interfaces, and uses a protocol, such as BGP, to learn addresses of the access interfaces on other switches in the network.
The Border Gateway Protocol (BGP) is a standardized exterior gateway protocol designed to exchange routing and reachability information among autonomous systems on the Internet. BGP makes routing decisions based on paths, network policies, or rule-sets configured by a network administrator. Internet Service Providers (ISP) use BGP to establish routing between one another and very large private IP (Internet Protocol) networks may use BGP internally. BGP neighbors are called peers, and are established by manual configuration between routers using TCP as the transport protocol.
For network resiliency through link redundancy, multi-homing techniques are used so that the same customer device is connected to two provider edge devices. In BGP EVPN, when a multi-homed customer MAC address is removed from one of the provider edge devices (PEs) to which it is multi-homed, there is a possibility that it will be temporarily withdrawn from all the PEs in the EVPN even if the MAC address is still reachable from other provider edge devices. This can lead to unwanted traffic loss. What is needed, therefore, is a way to dampen such temporary withdrawal of multi-homed MAC addresses and to remove them only if genuinely non-reachable.
The subject matter discussed in the background section should not be assumed to be prior art merely as a result of its mention in the background section. Similarly, a problem mentioned in the background section or associated with the subject matter of the background section should not be assumed to have been previously recognized in the prior art. The subject matter in the background section merely represents different approaches, which in and of themselves may also be inventions.